Reconstituted tobacco composition

ABSTRACT

The invention relates to a reconstituted-tobacco material. The smoking material contains a proportion of bibulous fibres, preferably in the range of 5 to 25 percent by weight of the smoking material and which are the substantially water insoluble, wet cross-linked derivatives of carboxymethyl cellulose. The reconstituted tobacco may be of the kind composed of tobacco which has been extracted, pulped, cast and dried and of concentrated tobacco extract added thereto. Advantageously the said tobacco comprises stem and lamina tobacco in a proportion of stem to lamina of substantially 25 to 30 percent and 75 to 70 percent lamina by weight.

United States Patent Nichol] RECONSTITUTED TOBACCO COMPOSITION [75] Inventor: Peter J. Nicholl, Southhampton,

England [73] Assignee: Brown & Williamson Tobacco Corporation, Louisville, KY

[22] Filed: Aug. 30, 1972 [21] Appl. No.: 285,056

30 Foreign Application Priority Dom Sept. 24, 1971 Great Britain 44721/71 [52] US. Cl. 131/17 R, 131/143, 131/144 5 l I! 1- .QklL'JL'JILY Ll 1'1? [58] Field of Search 131/17, 140, 2, 13

[56] References Cited UNITED STATES PATENTS 3,042,552 7/1962 Rosenberg et al. 131/140 C 3,097,653 7/1963 De Gooijer 131/140 C 3,125,098 3/1964 Osborne 131/140 C 3,145,717 8/1964 Osborne et al. l3l/143 X [451 Oct. 8, 1974 3,194,245 7/1965 Clarke 131/140 C 3,255,760 6/1966 Selke 131/143 X 3,298,378 l/l967 Stevens et a1 131/143 3,424,169 l/l969 Moren et al. 131/140 C Primary ExaminerMelvin D. Rein Attorney, Agent, or Firm-Finnegan, Henderson, F arabow & Garrett 57] ABSTRACT The invention relates to a reconstituted-tobacco material. The smoking material contains a proportion of bibulous fibres, preferably in the range of 5 to 25 percent by weight of the smoking material and which are the substantially water insoluble, wet cross-linked derivatives of carboxymethyl cellulose. The reconsti tuted tobacco may be of the kind composed of tobacco which has been extracted, pulped, cast and dried and of concentrated tobacco extract added thereto. Advantageously the said tobacco comprises stem and lamina tobacco in a proportion of stem to lamina of substantially 25 to 30 percent and 75 to 70 percent lamina by weight.

4 Claims, N0 Drawings RECONSTITUTED TOBACCO COMPOSITION This invention relates to the production of smoking materials comprising reconstituted tobacco.

Various processes have been developed for the production of tobacco in a reconstituted sheet form. These fall into three main categories which are briefly described as follows:

I. Production of a slurry of tobacco powder and an adhesive such as methyl cellulose or sodium carboxymethyl cellulose, casting the slurry on and endless steel band, and drying to produce a sheet suitable for use as a cigar wrapper or binder or as a cigarette filler.

2. Production of a colloidal slurry of tobacco which is formed into a sheet and used as described above.

3. Extraction of tobacco followed by pulping of the fibrous and cellular residue, casting the pulp on a continuous wire such as that of a Fourdrinier paper-making machine, and drying to form a base sheet to which a concentrate of the tobacco extract is added.

In the last process, commonly known as the paper process for tobacco reconstitution, the fibrous web formed on the paper-making wire is transferred, while wet, to felts which convey the web to the drying section of the paper-making machine. Drying may be achieved by various means, but a Yankee cylinder followed by smaller heated rolls is generally used. Proper transfer of the web from the wire to the felts is dependent on the wet strength of the web. This depends on the fibrous content of the pulp used and consequently on the stem (midrib) content of the pulp in relation to the lamina (stripped leaf without midrib) content.

Tobacco leaf, as grown generally has 25-30 percent by weight midrib and 75-70 percent lamina, so that the natural proportion of stem to lamina is about 1:3. In practice it is found that, in order to achieve economic operation of a paper machine for tobacco reconstitution, it is necessary to have a stem to lamina ratio of at least 1:1 and preferably at least 2: 1. The higher proportion of stem has a two-fold effect. Not only does it reduce web breakages during sheet formation and drying, but it also enables the wire speed, and thus the output, to be increased (In paper making, this is known as improving the runnability of the pulp). For this reason, it is necessary to increase the fibrous content of the pulp above that which occurs naturally in tobacco leaf. This can be achieved either by the inclusion of additional stem in the pulp or by the incorporation of cellulose fibres, for example of pinus sylvestris.

It has been found that the addition of as little as 5% by weight of cellulose fibres to a pulp of tobacco stem and lamina has a marked effect on the runnability, 5 percent of cellulose fibre being as effective as -20 percent of stem fibre. The addition of cellulose has, however, undesirable effects on the smoking product. The total smoke delivery is increased and the smoke produced has an acrid character which makes the product unacceptable to discerning smokers.

It is an object of the present invention to provide an alternative to the previously used cellulose fibers in reconstituted tobacco.

According to the invention, a reconstituted-tobacco smoking material includes a proportion of bibulous fibres.

Also according to the invention, the smoking material is produced from reconstituted tobacco in pulp, slurry or like form and has blends therewith the bibulous fibers, the composite blend being sheeted in final form a dry sheet from the blended material.

In this Specification and the appended claims, bibulous fibres are to be understood to be fibres of substantially water-insoluble, wet-cross-linked derivatives of carboxymethylcellulose. Such fibres and their production are described in British Patent Specification No. 1,236,313 (Buckeye Cellulose Corporation). They are produced by wet-cross-linking fibres of a water soluble carboxymethyl cellulose salt which has a degree of substitution of 0.8 1.0 carboxymethyl groups per unhydroglucose unit. The product is substantially water insoluble fibres which retain the fibrous form of the original cellulose raw material.

The bibulous fibres may comprise 2-50 percent by weight and preferably 5-25 percent by weight of the final smoking material.

The use of these fibres in reconstituted tobacco produced by a paper-making process can achieve the following advantages:

1. As with the incorporation of cellulose fibres, the addition of bibulous fibres improves the runnability of the pulp, thus enabling natural ratios of tobacco stem and lamina to be processed economically.

2. Since the bibulous fibres are carboxymethyl cellulose derivatives, they do not have a deleterious effect on the subjective character of the smoke from the reconstituted tobacco. The total smoke delivery is similar to that obtained when cellulose fibres are incorporated.

3. Difficulties hitherto arising in the impregnation of the base sheet, after drying, with a sufiiciently concentrated extract of tobacco are avoided. The final dry sheet may require to contain as much as 50-60 percent of soluble material. Depending on the types of tobacco processed, the absorbency of known base sheets may not be sufficient for this to be achieved unless extracts of high concentration, 30 percent or more, are used. In concentrating extracts to these high levels, irreversible chemical reactions may occur which result in the precipitation of previously soluble tobacco components. This can undesirably affect the subjective effects of the tobacco smoke from the reconstituted-tobacco product and also lead to difficulties in the control of the impregnation of the base sheet. These problems can be overcome by the incorporation in the reconstituted tobacco of bibulous fibres which allow the same content of soluble materials to be achieved in the final sheet despite the use of more dilute extracts for the impregnation.

The advantages of using bibulous fibres rather than cellulose fibres are not limited to the reconstitution of tobacco by a paper-making process. Thus, in one form of the slurry process in which cellulose fibres have heretofore been incorporated in the slurry, bibulous fibres may be added instead of the cellulose fibres with a resultant improvement in the subjective smoke character and total smoke delivery of the product, while mechanical properties similar to those obtained by using cellulose fibres are still achieved.

A method of preparing reconstituted tobacco containing bibulous fibres will now be more fully described by way of example. For comparison purposes, similar preparation of such tobacco containing cellulose fibres is also described:

U.S. flue-cured stems (leaf mid-ribs) threshed into 1-2 inches lengths were extracted three times with water at l00C. The stem:water ratio was maintained at 1:10 by weight and the extract was drained off after each extraction and retained for subsequent concentration. The fibrous residue was pumped, at 16 percent consistency, through a disk mill with a clearance of 0.035 inches between the plates, this being followed by beating in a Valley beater at 2 percent consistency for ten minutes.

U.S. flue-cured lamina (leaf without mid-ribs) was threshed into 1-2 square inch pieces and then extracted, milled and beaten as described above for the stems. The extract was again retained for subsequent concentration.

Bleached woodpulp (97 percent a-cellulose) was beaten at 1 percent consistency in a Valley beater for ten minutes.

Bibulous fibres obtained commercially as a dried pulp in sheet form were dispersed in water at 1 percent consistency without beating. The fibres were of dimensions similar to those of cellulose fibres used in normal paper making.

Stock components, obtained as described above, were blended to produce the following feedstocks (parts dry weight basis):

Stem Lamina Cellulose Bibulous fibre stocks containing the bibulous fibres were observed tobe as good as those of the feed stocks which contained cellulose fibres.

The extracts obtained from the stem and lamina were combined in the proportions of 100 parts of stem extract and 300 parts of lamina extract and the combined extracts were concentrated in a climbing-film evaporator to a solids content of percent. This concentrated extract was used, after any necessary adjustment of concentration, to impregnate the base sheets, by means of flooded-nip rollers, to a final level of 50 percent (on a dry-weight basis) of extracted soluble substances in the respective base sheets.

The reconstituted-tobacco sheets thus produced were made into cigarettes 70 mm long by 25 mm circumference. These were used for evaluation by standard machine smoking at one puff per minute of 35 ml volume and two seconds duration to a butt length of 23 mm and for subjective evaluation by a panel of cigarette smokers.

Results of the machine smoking were as follows:

.. ruf 29L... 7 or Base Sheet Cigarette particulate matter, Composition weight (mg) mg/cigarette 10% a-cellulose 860 I8 .20% a-cellulose 870 I6 10% bibulous fibre 860 I9 20% bibulous fibre 870 18 The differences in TPM deliveries observed, by collection of smoke on a Cambridge filter pad are of no practical significance.

The panel of smokers were unanimous in their preference for the cigarettes containing bibulous fibres. In particular, they noted that the cigarettes containing rot-cellulose fibre were irritating to the nose and eyes.

Samples of the base-sheets were also impregnated by dipping in the tobacco extract concentrated to the solids content of 25 percent. Free liquor was drained off and the impregnated sheets were dried at 100C for 16 hours. The level of impregnation was then determined by Soxhlet extraction with water for 6 hours followed by drying of the extracted residue at 100C for 16 hours.

Results were as follows:

Base Sheet Composition Level of impregnation 10% a-cellulose 52.5% 20% a-cellulose 53.3% l0% bibulous fibre 63.0% 20% bibulous fibre 60.0%

These results show that, for a given tobacco-extract concentration, it is possible to achieve higher levels of impregnation in the presence of bibulous fibres. This is also true in comparison with a base sheet containing no cellulose fibre. Such a sheet, when impregnated with the same tobacco extract, had a level of impregnation of 53.1 percent.

We claim:

1. A smoking composition in sheet form comprising essentially reconstituted tobacco and from 2 percent to about 50 percent by weight of bibulous fibers constituted of the wet cross-linked substantially water insoluble derivatives of carboxymethyl cellulose.

2. A smoking material according to claim 1, wherein the proportion of bibulous fibres is in the range of 5 to 25 percent by weight of the smoking material.

3. The smoking composition of claim 1 in which the reconstituted tobacco comprises fibrous extracted tobacco material and the composition includes a concentrated tobacco extract additive.

4. A smoking material according to claim 1, wherein the reconstituted tobacco comprises stem and lamina tobacco in a proportion of stem to lamina of substantially 25 to 30 percent stern and 75 to percent lam- 0 ina by weight. 

1. A SMOKING COMPOSITION IN SHEET FORM COMPRISING ESSENTIALLY RECONSTITUTED TOBACCO AND FROM 2 PERCENT TO ABOUT 50 PERCENT BY WEIGHT OF BIBULOUS FIBERS CONSTITUTED OF THE WET CROSS-LINKED SUBSTANTIALLY WATER INSOLUBLE DERIVATIVES OF CARBOCYMETHYL CELLULOSE.
 2. A smoking material according to claim 1, wherein the proportion of bibulous fibres is in the range of 5 to 25 percent by weight of the smoking material.
 3. The smoking composition of claim 1 in which the reconstituted tobacco comprises fibrous extracted tobacco material and the composition includes a concentrated tobacco extract additive.
 4. A smoking material according to claim 1, wherein the reconstituted tobacco comprises stem and lamina tobacco in a proportion of stem to lamina of substantially 25 to 30 percent stem and 75 to 70 percent lamina by weight. 